Mummified fossil of Keteleeria from the Late Pleistocene of Maoming Basin, South China, and its phytogeographical and paleoecological implications

Abstract

Keteleeria is a small genus of Pinaceae now mainly restricted to eastern Asia. Although this genus has been documented with a wide distribution in the geologic record of Europe, North America, and Asia, its history in low‐latitude areas (including South China) has remained obscure. In this paper, a fossil wood of Keteleeria sp. is described from the Late Pleistocene (29–27 ka BP) of the Maoming Basin, South China. This wood is the most ancient megafossil evidence of Keteleeria within the modern distribution area of this genus. The fossil records of Keteleeria suggests that this thermophyllous genus migrated into South China by the Middle Pleistocene escaping from glacial cooling and became widespread over this region in the Late Pleistocene beginning from the interglacial stage preceding the Last Glacial Maximum. The analysis of growth rings in the fossil wood and its comparison with those of modern Keteleeria davidiana (Bertrand) Beissner indicates that in the Late Pleistocene of Maoming Basin (29–27 ka BP) there was a humid climate with less pronounced seasonality of precipitation than that seen in the subtropical monsoonal climate of modern northeastern Vietnam. Apparently, the Maoming Basin was influenced by interglacial regime with summer–monsoon circulation. The previously proposed method to distinguish between evergreen and deciduous conifers based on growth ring anatomy, is not reliable because of the wide variance and ambiguity in its results.

Mummified fruits of Canarium from the upper Pleistocene of South China

“…Bertrand) Beissn., a monsoon-influenced humid subtropical climate with hot wet summers and cool dry winters was interpreted for the Maoming Basin region during late Pleistocene. 21 , 42 These conditions are similar to the humid subtropical climate classified as Cwa, under the Köppen climate classification, 45 , 46 that prevails at present in northeastern Vietnam.…”

“…The fossil plant assemblage associated with C. maomingense at the locality includes identified to date conifers of the genera Pinus and Keteleeria (Pinaceae) and angiosperms belonging to Elaeocarpus (Elaeocarpaceae), Liquidambar formosana Hance (Altingiaceae), and Fagaceae. 21 , 42 , 43 Most of these taxa occur in the modern subtropical evergreen broad-leaved and mixed forests of Eastern Asia. 38 , 44 Based on growth ring analysis of fossil wood of Keteleeria sp.…”

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Figure 1 Location and lithology of the fossil site (modified from Huang et al. 21 ) (A) Geographic map showing the location of the Zhenjiang opencast mine within the Maoming Basin in Guangdong Province, South China (base map from d-maps: https://d-maps.com ). (B) View of the plant-bearing section.

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Early Cretaceous <em>Keteleerioxylon</em> Wood in Songliao Basin, Northeast China, and Its Geographic and Environmental Implications

“…Keteleeria sp. from Guangdong, China differs from the woods under study in having uniseriate to biseriate pits on the radial walls of tracheids, in lower rays, and in having fewer pits per crossfield [31].…”

“…of Guangdong, China. and its CSDM curves showed both left and right skews [31]. But the radial cells in three growth rings of Keteleeria sp.…”